Container Inspection Method and System

ABSTRACT

[PROBLEM] To provide a novel inspection method and system of a container enabling inspection of excess entrainment of air inside a flexible container and inspection of seal defects of a flexible container to be performed by a single technique simultaneously, enabling a full run of flexible containers to be continuously inspected on the production line, and giving a high inspection precision.  
     [MEANS FOR SOLUTION] Inspecting for seal defects of a container and excess entrainment of air in a container in an inspected object comprised of a flexible container in which a liquid is filled, during which placing the inspected object in an air-tight container, sucking out the air in the air-tight container to reduce the pressure sufficient to make container outer walls of the inspected object expand, measuring an expansion dimension of the container outer walls, and comparing it with a preset threshold value to judge the quality of the inspected object.

TECHNICAL FIELD

The present invention relates to an inspection method and system for apaper pack containing a liquid, a blood transfusion bag, or otherflexible container.

BACKGROUND ART

For example, when filling a paper pack with a beverage, air is sometimesentrained. If excessive air is entrained in the container, insufficientfilling, spoilage of the filled beverage, and other trouble with theproduct occur.

As a means for inspecting for excess entrainment of air in this type offlexible container, it is known to place the inspected object in whichliquid is filled in an air-tight space, reduce the pressure, detect thepresence of any expansion of the flexible container outer walls, and,when the outer walls expand (change), judge that excess air isentrained, while when no change occurs, judge that the product is good(see Patent Document 1).

On the other hand, another problem with this type of flexible containeris the problem of liquid leakage. Liquid leakage is mainly due to a poorheat seal of the container, pinholes in the container material, andother seal defects. This causes spoilage of the filled beverage, so isconsidered a serious defect in quality control.

As means for inspecting for this liquid leakage, it is known to pressthe inspected object in which a liquid is filled and inspect for anyleakage of the liquid. According to this, liquid leaked from theinspected object is inspected for by running a current betweenelectrodes of an inspection unit (see Patent Document 2).

As explained above, in the past, the inspection of excess airentrainment in a flexible container and the inspect of liquid leakagewere conducted by separate, different techniques. This was troublesomeand inefficient. Further, in the means for inspecting for liquidleakage, the leaked liquid contaminated the inspection system and madethe inspection by conduction no longer accurate, so the inspectionsystem had to be cleaned each time and therefore continuous inspectionof the entire run of flexible containers was not possible.

Patent Document 1: Japanese Patent Publication (B2) No. H8-5471

Patent Document 2: Specification of Japanese Patent No. 2694483

Disclosure of the Invention

Problem to be Solved by the Invention

The present invention was proposed in consideration of this situationand has as its object the provision of an inspection method and systemenabling simultaneous inspection of excess entrainment of air in aflexible container and inspection of seal defects of a flexiblecontainer by a single technique. Further, the present invention has asits object to provide a novel inspection method and system enabling anentire run of flexible containers to be continuously inspected on aproduction line and a high inspection precision to be obtained.

Means for Solving the Problem

That is, the aspect of the invention of claim 1 relates to an inspectionmethod of a container comprising inspecting for seal defects of acontainer and excess entrainment of air in a container in an inspectedobject comprised of a flexible container in which a liquid is filled,during which placing the inspected object in an air-tight container,sucking out the air in the air-tight container to reduce the pressuresufficient to make container outer walls of the inspected object expand,measuring an expansion dimension of the container outer walls, andjudging quality of the inspected object.

The aspect of the invention of claim 2 provides an inspection method ofa container as set forth in claim 1 wherein the inspected object isjudged for quality by measuring the expansion dimension of the containerouter walls at a predetermined pressure reduction value of the pressurereduction process and comparing it with a predetermined threshold value.

The aspect of the invention of claim 3 provides an inspection method ofa container as set forth in claim 1 wherein a peak pressure reductionsetting relating to the pressure reduction is atmospheric pressure minus94 to 100 kPa.

The aspect of the invention of claim 4 provides an inspection method ofa container as set forth in claim 1 wherein before reducing the pressurefor measuring the expansion dimension of the container, the inspectedobject is preliminarily reduced in pressure and restored.

The aspect of the invention of claim 5 relates to an inspection systemof a container provided with a conveying means for conveying aninspected object comprised of a flexible container in which a liquid isfilled, an air-tight container for holding the inspected object to beable to be inserted and taken out by the conveying means, a pressurereducing means for sucking out the air in the air-tight container andreducing the pressure sufficient for making the container outer walls ofthe inspected object expand, a measuring means for measuring anexpansion dimension of the container outer walls in the pressurereduction process, and a processing means for judging quality of thecontainer by the expansion dimension of the container outer walls.

The aspect of the invention of claim 6 provides an inspection system ofa container as set forth in claim 5 wherein the measuring means measuresthe expansion dimension of the container outer walls at a predeterminedpressure reduction value of the pressure reduction process, and theprocessing means compares the measured value with a predeterminedthreshold value.

The aspect of the invention of claim 7 provides an inspection system ofa container as set forth in claim 5 wherein the air-tight containerholds a plurality of inspected objects, and the measuring means andprocessing means function for each of the inspected objects.

The aspect of the invention of claim 8 provides an inspection system ofa container as set forth in claim 7 wherein a plurality of the air-tightcontainers are arrayed and alternately or successively connected to theconveying means, the inspected objects are successively placed in theair-tight containers, and the inspected objects are discharged frominside the air-tight containers to the conveying means.

The aspect of the invention of claim 9 provides an inspection system ofa container as set forth in claim 5 wherein the air-tight containerhouses a single inspected object.

The aspect of the invention of claim 10 provides an inspection system ofa container as set forth in claim 9 wherein a plurality of the air-tightcontainers are arrayed and successively connected to the conveyingmeans, the inspected objects are successively housed in the air-tightcontainers, and the inspected objects are discharged from inside theair-tight containers to the conveying means.

The aspect of the invention of claim 11 provides an inspection system ofa container as set forth in claim 5 which covers an inspected objectwith little air space or no air space in the container after thecontainer is filled with the liquid and an inspected object with nopositive pressure in the container.

Effect of the Invention

According to the inspection method of a container according to theaspect of the invention of claim 1, the method comprises inspecting forseal defects of a container and excess entrainment of air in a containerin an inspected object comprised of a flexible container in which aliquid is filled, during which placing the inspected object in anair-tight container, sucking out the air in the air-tight container toreduce the pressure sufficient to make container outer walls of theinspected object expand, measuring an expansion dimension of thecontainer outer walls, and judging excess entrainment of air of theinspected object and defective and good sealing by the difference. Forthis reason, the single technique of reducing the pressure sufficientlyfor causing expansion of the container outer walls of the inspectedobject enables inspection of excess entrainment of air in a containerand inspection of seal defects of a container simultaneously andprecisely.

According to the aspect of the invention of claim 2, in claim 1, theinspected object is judged for quality by measuring the expansiondimension of the container outer walls at a predetermined pressurereduction value of the pressure reduction process and comparing it witha predetermined threshold value, so the inspection can be performedprecisely and efficiently.

According to the aspect of the invention of claim 3, in claim 1, a peakpressure reduction setting relating to the pressure reduction is madeatmospheric pressure minus 94 to 100 kPa, so even inspection of aflexible container provided with a certain degree of rigidity can beperformed precisely and efficiently by a high degree of vacuum.

According to the aspect of the invention of claim 4, in claim 1, beforereducing the pressure for measuring the expansion dimension of thecontainer, the inspected object is preliminarily reduced in pressure andrestored, whereby the state of the liquid filled inside the inspectedobject shifts to a state quickly and clearly causing the expansion ofthe container outer walls at the time of reduction of pressure at themeasurement and the expansion dimension of the container outer walls canbe accurately measured in a short time, so inspection can be conductedat a higher performance and high precision.

The aspect of the invention of claim 5 relates to an invention of aninspection system provided with a conveying means for conveying aninspected object comprised of a flexible container in which a liquid isfilled, an air-tight container for holding the inspected object to beable to be inserted and taken out by the conveying means, a pressurereducing means for sucking out the air in the air-tight container andreducing the pressure sufficient for making the container outer walls ofthe inspected object expand, a measuring means for measuring anexpansion dimension of the container outer walls in the pressurereduction process, and a processing means for judging quality of thecontainer by the expansion dimension of the container outer walls, so asystem can be provided enabling inspection of excess entrainment of airin a container and inspection of seal defects of a container to beperformed simultaneously and precisely by a single system.

According to the aspect of the invention of claim 6, in claim 5, themeasuring means measures the expansion dimension of the container outerwalls at a predetermined pressure reduction value of the pressurereduction process, and the processing means compares the measured valuewith a predetermined threshold value, so the container can be preciselyand efficiently inspected.

According to the aspect of the invention of claim 7, in claim 5, theair-tight container holds a plurality of inspected objects, and themeasuring means and processing means function for each of the inspectedobjects, so a large number of containers can be simultaneously inspectedinside the air-tight container. For this reason, there is the effectthat high performance inspection can be performed by a simple system.

According to the aspect of the invention of claim 8, in claim 7, aplurality of the air-tight containers are arrayed and alternately orsuccessively connected to the conveying means, the inspected objects aresuccessively placed in the air-tight containers, and the inspectedobjects are discharged from inside the air-tight containers to theconveying means, so the inspected objects can be inspected by a highperformance.

According to the aspect of the invention of claim 9, in claim 5, theair-tight container houses a single inspected object, so the freedom ofdesign of the inspection system structure is increased for the varioustypes and shapes of inspected containers and a wide range of types ofcontainer can be inspected precisely and efficiently.

According to the aspect of the invention of claim 10, in claim 9, aplurality of the air-tight containers are arrayed and successivelyconnected to the conveying means, the inspected objects are successivelyhoused in the air-tight containers, and the inspected objects aredischarged from inside the air-tight containers to the conveying means,so the containers can be continuously efficiently inspected.

According to the aspect of the invention of claim 11, in claim 5, theinspection system covers an inspected object with little air space(content of container of air or inert gas) or no air space in thecontainer after the container is filled with the liquid and an inspectedobject with no positive pressure in the container, so the inspectedobject can be inspected precisely and efficiently.

Best Mode for Working the Invention

Below, the present invention will be explained in detail in accordancewith the embodiments of the attached drawings. FIG. 1 is a schematicexplanatory view of the main parts of a system for inspecting acontainer of the present invention, FIG. 2 is a graph illustrating therelationship between the total value of expansion dimensions of the twosides of the container outer walls in the pressure reduction process andthe pressure and elapsed time, FIG. 3 is a graph illustrating therelationship between the total value of expansion dimensions of the twosides of the container outer walls when preliminarily reduced inpressure and restored and the pressure and elapsed time, FIG. 4 is aplan view of main parts of an embodiment of an inspection systemutilizing an air-tight container housing a plurality of inspectedobjects, FIG. 5 is a front view of FIG. 4, FIG. 6 is a plan view showingdetails of a driving means arranged at the top in FIG. 4, FIG. 7 is aview along the arrow X of FIG. 4, FIG. 8 is a plan view of an embodimentof an inspection system utilizing air-tight containers housing singleinspected objects, and FIG. 9 is a basic cross-sectional view along theline Y-Y of FIG. 8.

The inspection method of a container according to the aspect of theinvention of claim 1 inspects for seal defects of a container in aninspected object comprised of a paper pack or other flexible containerin which a beverage or other liquid is filled and for excess entrainmentof air in a container. The inspection method of the present inventionplaces an inspected object in an air-tight container, sucks air out frominside the air-tight container to reduce the pressure sufficiently forcausing the container outer walls of the inspected object to expand, andmeasures an expansion dimension of the container outer walls to judgethe container.

The embodiment shown in FIG. 1 covers an inspected object M comprised ofa box-shaped paper pack container in which a beverage is filled. Theinspected object M is placed in an air-tight container 30 of aninspection system 10. The air-tight container 30 is communicated with apressure reducing means 40 having a known vacuum pump (not shown) as acomponent through vacuum piping 35. The air inside the air-tightcontainer 30 is sucked out by the vacuum pump to reduce the pressure toa negative pressure sufficient for the container outer walls K1, K2 ofthe inspected object M to expand.

The expansion dimensions of the container outer walls K1, K2 of theinspected object M are measured by measuring means 50A, 50B utilizingknown displacement sensors etc. which measure the distance to thecontainer outer walls of the inspected object M and transmit the datathrough cables S1, S2 to a known processing means 60. The processingmeans 60 calculates the difference in distances in the air-tightcontainer 30 before and after pressure reduction and judges the qualityof the inspected object M. Note that in the present embodiment, theexpansion dimensions of the outer walls of the two sides of thecontainer can be easily measured, so by calculating the expansiondimensions of the outer walls of the two sides, then adding theexpansion dimensions of the two sides of the container to obtain asingle container expansion dimension and comparing the amount of changeof the expansion dimensions of the two sides of the container, theinspection precision is improved. Reference numeral 36 indicates apressure measurement system, 51, 52 measurement systems, and S3 a cable.

Note that in the present embodiment, the explanation was given of theexample of an inspected object M comprised of a box-shaped paper packcontainer in which a beverage is filled, but the flexible container mayalso be made of a plastic, aluminum foil, etc., may be shaped as a cup,pouch, or other bag-shaped container etc. Further, the filled liquid isnot limited to a beverage and may also be blood for transfusions etc. Inthis way, the present invention can be applied to various combinationsof materials, container shapes, and filled liquids. Further, in thepresent embodiment, the total value of the expansion dimensions of theouter walls of the two sides of a paper pack container was used toinspect the inspected object, but for a cup-shaped or bag-shapedcontainer or other such container where only the expansion dimension ofone direction of the container outer walls can be easily measured, it isalso possible to measure the expansion dimension of one location toinspect the container according to the present invention.

In the inspection of the inspected object M, even an inspected object Mcomprised of a container in which a liquid is sealed but excessive airis not entrained has solute air in the liquid inside the inspectedobject M and small amounts of air entering when filling the beverage, sothe reduction of pressure causes the container outer walls to expand.However, inspected objects M where air is excessively entrained and oneswith seal defects start to expand while the pressure reduction value isstill small compared with normal inspected objects, that is, goodproducts. Further, the expansion dimensions of the container outer wallsat the same pressure reduction value in the pressure reduction processbecome larger. The present invention, based on this discovery, reducesthe pressure sufficiently for causing expansion of the container outerwalls of an inspected object, measures an expansion dimension of thecontainer outer walls, and compares the expansion dimension of the outerwalls at a predetermined pressure reduction value with a presetthreshold value so as to simultaneously inspect for excess entrainmentof air and seal defects.

That is, the container outer walls of good products and inspectedobjects M with excess entrainment of air and seal defects all expand inthe pressure reduction process in the air-tight container 30, but theexpansion dimensions differ. Further, for each type of container orfilled substance of the inspected object covered, there is a setting ofpressure reduction at which the difference of the expansion dimensionswill be significant and be discernable (peak pressure reduction setting)and a pressure reduction value (inspection pressure reduction value)suitable for measuring the expansion dimension and comparing it with athreshold value. For this reason, the inspected object covered is testedto find in advance the suitable peak pressure reduction setting of thepressure reduction, inspection pressure reduction value for measuringthe expansion dimension, and the threshold value, and these conditionsare used for inspection of the inspected object at the time ofproduction.

The graph illustrated in the following FIG. 2 shows the relationshipbetween the total value of the expansion dimensions of the two sides ofthe container outer walls and the pressure and elapsed time in apressure reduction process when making the peak pressure reductionsetting of the pressure reduction the atmospheric pressure minus 98.Note that the inspected object used here is a 30 mm×40 mm×85 mm paperpack container in which a milk beverage is filled. For an inspectedobject with excess entrainment of air, 0.2 cc of air was intentionallyinjected into the inspected object and mixed with the milk beverage,while for an inspected object with seal defects, a paper pack containerin which a 0.2 mmφ hole was intentionally made was used.

As illustrated above, the container outer walls start to expand from thestart of pressure reduction of the air-tight container, but theexpansion is fastest in the order of excess entrainment of air, sealdefects, and then good products. This difference in the speeds ofexpansion of the container outer walls is believed due to the airpresent inside the container of an inspected object with excessentrainment of air reacting the fastest to the drop in ambient pressure,causing an expansion of volume, and causing expansion of the containerouter walls. Further, in an inspected object with seal defects, it isbelieved that due to the effects of the seal defect part of thecontainer, in this case, the 0.2φ hole, the filled liquid reacted fasterthan a good product to the drop in ambient pressure and causedseparation of the solute air in the liquid, and the separated airexpanded and caused the container outer walls to expand, therefore theinspected object expanded faster than a good product. Note that even inthe good inspected object, the outer walls of the flexible container arepulled by the ambient negative pressure resulting in the inside of thecontainer becoming a negative pressure, whereby the air in the filledliquid gently separates and causes the container outer walls to expand,but slower than an inspected object with seal defects.

For this reason, in FIG. 2, if setting for example, the atmosphericpressure minus 96 kPa, exhibited by the pressure inside the air-tightcontainer 10 shown by the inspection pressure reduction value Pk, withrespect to the peak pressure reduction setting Pt of the pressurereduction constituted by the atmospheric pressure minus 98 kPa, inadvance as the pressure for inspection by measurement of the expansiondimension of the inspected object and measuring the expansion dimensionof the container outer walls at that time, it is possible to judge thequality of the inspected object as follows: That is, if setting aninspected object M exhibiting an expansion dimension of the containerouter walls at the inspection pressure reduction value Pk under the goodlimit dimension Lr as the threshold for good products, setting aninspected object M exhibiting an expansion dimension over the good limitdimension Lr and under the seal defect dimension Lm as the threshold forseal defects, and setting an inspected object M exhibiting an expansiondimension over the seal defect dimension Lm as the threshold value forexcess entrainment of air, inspected objects exhibiting the expansiondimensions L1, L2, and L3 can be identified as being good products andhaving seal defects and excess entrainment of air.

Further, according to the present invention, when making the peakpressure reduction setting for pressure reduction in the air-tightcontainer the atmospheric pressure minus 94 kPa to 100 kPa as describedin claim 3, it is possible to effectively identify good products, sealdefects, and excess entrainment of air for paper packs and otherflexible containers with relatively high rigidity. That is, at anegative pressure of less than atmospheric pressure minus 94 kPa, apaper pack or other container with relatively high rigidity does notsufficiently expand in a short time, so it was believed that efficientinspection and identification of inspected objects were difficult.Further, a peak pressure reduction setting in a high vacuum ofatmospheric pressure minus 100 kPa or more is not required in practice.Considering the performance, cost, etc. of the vacuum pump, while notparticularly limited to this, atmospheric pressure minus 94 kPa to 100kPa in range may be employed as the region of the peak pressurereduction setting for good precision inspection of a large number ofinspected objects.

Note that in the above explanation, the expansion dimension of theinspected object M at the designated inspection pressure reduction valuePk was compared with threshold values to identify good products anddefective products. However, the pressure drop inside the air-tightcontainer 30 is proportional to the time approximately after the startof pressure reduction, so instead of the designated inspection pressurereduction value Pk, it is also possible to measure the expansiondimension of the inspected object M at the designated elapsed time Tkafter the start of pressure reduction and compare this with thepredesignated threshold values to inspect an inspected object M.

Note that the data of the pressure inside the air-tight container 30 andexpansion dimension of the container outer walls illustrated in FIG. 2change due to the material and dimensions of the inspected objectcontainer, the type of the filled liquid, the size of the air-tightcontainer, the capacity of the vacuum pump, the peak pressure reductionsetting at the time of pressure reduction, etc. In this way, if theinspection conditions differ, different curves are obtained in thegraph, so the suitable peak pressure reduction setting Pt and inspectionpressure reduction value Pk for the inspection conditions and theinspected object and system are selected for inspection of the inspectedobject. Further, even when identifying the quality of inspected objectsby measuring the expansion dimension at one location of the containersuch as with cup-shaped and bag-shaped containers, a similarly designedtest is conducted in advance to determine the preferable inspectionconditions for inspection of the inspected object.

Further, according to the present invention, as described in claim 11,when inspecting a container with little air space or a container with noair space and a container with no positive pressure inside as theinspected object, the difference in the amount of change of theexpansion dimensions of the two sides of the container accompanyingpressure reduction in the air-tight containers 30 is particularlyclearly expressed, so it is possible to precisely identify inspectedobjects of good products, seal defects, and excess entrainment of air.

FIG. 3 is a graph showing the relationship between the total value ofthe expansion dimensions of the two sides of the container outer wallsand the pressure when performing the preliminary pressure reduction andrestoration of an inspected object according to the aspect of theinvention of claim 4. The pressure in the air-tight container 30 isreduced once to P1, then restored to atmospheric pressure. At this time,the air in the beverage or other filled liquid in the containerseparates from the filled liquid in advance in the pressure reductionprocess whereby, at the time of inspection of the inspected object M,the expansion of the container outer walls is accelerated and thedifferences due to the state of the inspected object appear moreclearly. For this reason, compared with when not conducting preliminarypressure reduction, it becomes possible to measure difference in theinspected object in a short time and more clearly identify excessentrainment of air, seal defects, and good products and possible toperform higher precision inspection more efficiently.

That is, compared with the graph in the case of not performing thepreliminary pressure reduction shown in FIG. 2, when performing thepreliminary pressure reduction of FIG. 3, expansion and enlargement ofthe outer walls of the inspected object occurs in a short time, thedifference in expansion dimensions of the inspected object M at thedesignated inspection pressure reduction value Pk becomes larger, andexcess entrainment of air, seal defects, and good products can be moreclearly identified and the inspection precision and inspection abilitycan be improved.

Next, in an embodiment of an inspection system using air-tightcontainers holding a plurality of inspected objects M shown in FIG. 4and FIG. 5, the inspection system 10 is provided with a transportconveyor 20 as a conveying means, two air-tight containers 30A, 30B, apressure reducing means 40, a measuring means 50, and a not shownprocessing means 60. The transport conveyor 20 conveys the containers Mto the air-tight container 30A or 30B and, after the inspection, conveysthe inspected objects M discharged from the air-tight container 30A, 30Bdownstream. Further, the air-tight containers 30A, 30B stores inspectedobjects M on the transport conveyor 20 inside them, then are madeair-tight as explained in detail later and are connected with the vacuumpump of the pressure reducing means 40 by the vacuum piping 35. Due tothis, air inside the air-tight containers 30A, 30B is sucked out toreduce the pressure.

As shown in FIG. 4, in this embodiment, the air-tight containers 30 aretwo air-tight containers 30A, 30B which move back and forthintermittently over the transport conveyor 20 as shown by the arrow Dwhereby one air-tight container 30, in the illustration, the air-tightcontainer 30B, stops at a position above the transport conveyor 20. Theair-tight container 30B stopping over the transport conveyor 20 opensits exit door 31B and discharges the plurality of inspected objects Minside it on the transport conveyor 20. After this, the air-tightcontainer 30B closes its exit door 31B, opens its inlet door 31A, takesin a plurality of inspected objects M from the transport conveyor 20 andstores them inside, then moves to the inspection position of theair-tight container 30C shown by the broken line. Further, at this time,the other air-tight container 30A moves over the transport conveyor 20and discharges its inside inspected objects M to the transport conveyor20 and picks up new inspected objects M inside it.

Note that the step of receiving new inspected objects M from thetransport conveyor 20 and storing them inside the air-tight container 30is performed by closing the exit door 31B, opening the inlet door 31A,and, in that state, using the known means of a container feed system 15installed at the upstream side of the transport conveyor 20 to count andfeed a predetermined number of inspected objects. Further, the air-tightcontainer 30B holding the new inspected objects M moves to theinspection position of the air-tight container 30C shown by the brokenline where the inspected objects M undergo predetermined inspectionexplained in detail later. Further, similarly, the air-tight container30A holding new inspected objects M at the position of the air-tightcontainer 30B performs inspection at the inspection position of theair-tight container 30A shown by the solid line. That is, the twoair-tight containers 30A, 30B alternately move in a directionperpendicular to the advancing direction of the transport conveyor toinspect the inspected objects M at the inspection positions of the twosides of the transport conveyor 20.

In FIG. 5, the air-tight container 30B (30A) is supported on thetransport conveyor 20 by the air-tight container movement system 16 andmoves as explained in detail later to be alternately connected to theconveying means constituted by the transport conveyor 20. The air-tightcontainer 30B (30A) successively holds a plurality of inspected objectsM. Further, the inspected objects M which are finished being inspectedare discharged from the air-tight container 30B (30A) to the transportconveyor 20. Further, the air-tight containers 30B and 30A are supportedfixed integrally to the movement brackets 19, while the movementbrackets 19 are supported slidably with respect to the movement rails21.

Further, as shown in FIG. 6, the air-tight container movement system 16is supported by the support bracket 17 and provided over the transportconveyor 20 and air-tight containers 30A, 30B. Note that in the figure,the state is shown where the air-tight containers 30A are moved topositions corresponding to the transport conveyor 20.

As shown in FIG. 7, the movement brackets 19 are fixed to a timing belt23, are moved by a drive motor 18 through pulleys 22 as shown by thearrow, and move and position the air-tight containers 30A and 30B in theleft-right direction of the conveyor 20. The air-tight plates 24arranged below the inspection positions of the illustrated air-tightcontainers 30A and 30C are driven by the lift cylinders 25 to move inthe up-down direction so as to make the bottoms of the air-tightcontainers 30A and 30C (30B) air-tight and enable reduction of thepressure inside. Further, the slide plate 26 has the function ofenabling the inspected objects M held inside the open bottom air-tightcontainers 30A, 30B to slide smoothly on its top surface to move to theinspection positions when moving to the left and right.

As explained above, even in a system which houses pluralities ofinspected objects M in the air-tight containers 30A, 30B andsimultaneously inspects the pluralities of inspected objects M,basically the inspection is performed in the same way as the inspectionprocess explained in FIG. 1. Further, as shown specifically in FIG. 4and FIG. 7, a plurality of measuring means 50A, 50B are providedcorresponding to the inspected objects M, individually measure thedistances to the container outer walls, and transmit the data to theprocessing means 60 which then individually processes the data,calculates the total values of the expansion dimensions of the two sidesof the container outer walls of the inspected objects, individuallycompares them with the threshold values, and thereby inspects theinspected objects.

Further, the above-mentioned results of judgment of the inspectedobjects are deemed as individual data linked with the positions of theinspected objects M in the air-tight container 30, that is, their orderin the arrays, and are stored in the processing means 60 as individualdata corresponding to the inspected objects. Further, the inspectedobjects discharged to the transport conveyor 20 are conveyed downstreamduring which a not shown container pushout system or other knowncontainer ejection system is used to eject objects from the conveyor atdifferent locations according to whether they exhibit excess entrainmentof air or seal defects. Note that it is also possible to eject thedefective products at the same locations on the conveyor or, instead ofejecting the defective products from the transport conveyor 20, issue asignal indicating the occurrence of a defective container and performother post-processing. This may be freely selected in accordance withthe characteristics of the production line inspecting the inspectedobjects M.

Note that when the inspected object M is a cup-shaped or a bag-shapedcontainer and the expansion dimension is measured at a single point onthe container outer walls such as the top surface of the inspectedobject M, calculation of the total value of the expansion dimensions atthe two sides explained above becomes unnecessary. The expansiondimension at a single point of the outer walls of the inspected object Mis measured for inspection of the inspected object M, the inspectedobject M is discharged to the transport conveyor, then the object issubjected to the predetermined processing.

Note that as an embodiment where a plurality of air-tight containersholding pluralities of inspected objects M, the case of two air-tightcontainers 30A, 30B moving back and forth was explained, but it is alsopossible to employ a rotary type configuration in which three or moreair-tight containers 30 rotate above a vertical direction or horizontaldirection axis. The present invention is not limited to the aboveembodiment. With the scope of the gist of the present invention, it ispossible to utilize other configurations of container inspectionsystems.

Below, in FIG. 8, an embodiment of the inspection system 10 in the caseof utilizing air-tight containers holding single inspected objects M andusing cylindrically shaped cups as the inspected objects M will beexplained. As illustrated, the inspection system 10 is a rotary typewhich rotates as shown by the arrow. The inspected objects M areconveyed on a transport conveyor 20 and inched forward by an infieldscrew 11 through a feed star wheel 12 to be fed onto the rotary disk 13to be inspected. Further, the inspected objects M after the inspectionare discharged through an exhaust star wheel 14 to the transportconveyor 20.

The rotary disk 13 is provided with air-tight containers 30 moving inthe up-down direction, explained in detail later, corresponding to feedpositions of the inspected objects M. The air-tight containers 30 riseup at the positions of the feed star wheel 12 and exhaust star wheel 14so that without interference with the air-tight containers 30 theinspected objects M may be fed onto the rotary disk 13 and the inspectedobjects M may be discharged onto the transport conveyor 20.

As shown in FIG. 9, each air-tight container 30 moves up and down by alift cylinder 37 via an up-down movement bracket 39 to enable feeding ofan inspected object M to the air-tight container 30 and its discharge.Further, air inside the air-tight container 30 is sucked out forreduction of pressure through vacuum piping 35 and rotary boards 38A,38B and flexible vacuum piping 35A by a not shown vacuum pump. Further,the pressure inside the air-tight container 30 and the expansiondimension of the top surface of the inspected object M measured by themeasuring means 50 are taken out to the outside through cables S1, S3and a not shown rotary joint and processed. Reference numerals 36A andS1A indicate cables.

Note that in the embodiments in which a plurality of the air-tightcontainers are arrayed, the explanation was given of the case ofutilizing cylindrically shaped air-tight containers 30 for cylindricallyshaped inspected objects M, but the present invention is not limited tothese embodiments and may also use box-shaped air-tight containers 30for box-shaped inspected objects M such as paper packs and bloodtransfusion bags. Within the scope of the gist of the present invention,it is possible to utilize other configurations of container inspectionsystems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory view of the main parts of a system forinspecting a container of the present invention.

FIG. 2 is a graph illustrating the relationship between the total valueof expansion dimensions of the two sides of the container outer walls inthe pressure reduction process and the pressure and elapsed time.

FIG. 3 is a graph illustrating the relationship between the total valueof expansion dimensions of the two sides of the container outer wallswhen preliminarily reduced in pressure and restored and the pressure andelapsed time.

FIG. 4 is a plan view of main parts of an embodiment of an inspectionsystem utilizing an air-tight container housing a plurality of inspectedobjects.

FIG. 5 is a front view of FIG. 4.

FIG. 6 is a plan view showing details of a driving means arranged at thetop in FIG. 4.

FIG. 7 is a view along the arrow X of FIG. 4.

FIG. 8 is a plan view of an embodiment of an inspection system utilizingair-tight containers housing single inspected objects.

FIG. 9 is a basic cross-sectional view along the line Y-Y of FIG. 8.

DESCRIPTION OF NOTATIONS

10 inspection system

11 infield screw

12 feed star wheel

13 rotary disk

14 exhaust star wheel

16 air-tight container movement system

17 support bracket

19 movement bracket

20 transport conveyor (conveying means)

21 movement rail

22 pulley

23 timing belt

24 air-tight plate

25 lift cylinder

26 slide plate

30, 30A to 30C air-tight container

31A inlet door

31B exit door

35 vacuum piping

36 pressure measurement system

37 lift cylinder

38A, 38B rotary board

39 up-down movement bracket

40 pressure reducing means

50, 50A, 50B measuring means

51, 52 measurement system

60 processing means

K1 container outer walls

K2 container outer walls

L1 to L3 expansion dimensions

Lm seal defect dimensions

Lr good limit dimensions

M inspected object

Pk inspection pressure reduction value

Pt peak pressure reduction setting

S1 to S3 cable

Tk elapsed time

1. An inspection method of a container comprising inspecting for sealdefects of a container and excess entrainment of air in a container inan inspected object comprised of a flexible container in which a liquidis filled, during which placing said inspected object in an air-tightcontainer, sucking out the air in said air-tight container to reduce thepressure sufficient to make container outer walls of said inspectedobject expand, measuring an expansion dimension of said container outerwalls, and judging quality of the inspected object.
 2. An inspectionmethod of a container as set forth in claim 1 wherein said inspectedobject is judged for quality by measuring the expansion dimension ofsaid container outer walls at a predetermined pressure reduction valueof said pressure reduction process and comparing it with a predeterminedthreshold value.
 3. An inspection method of a container as set forth inclaim 1 wherein a peak pressure reduction setting relating to saidpressure reduction is atmospheric pressure minus 94 to 100 kPa.
 4. Aninspection method of a container as set forth in claim 1 wherein beforereducing the pressure for measuring the expansion dimension of saidcontainer, said inspected object is preliminarily reduced in pressureand restored.
 5. An inspection system of a container provided with aconveying means for conveying an inspected object comprised of aflexible container in which a liquid is filled, an air-tight containerfor holding said inspected object to be able to be inserted and takenout by said conveying means, a pressure reducing means for sucking outthe air in said air-tight container and reducing the pressure sufficientfor making the container outer walls of said inspected object expand, ameasuring means for measuring an expansion dimension of said containerouter walls in said pressure reduction process, and a processing meansfor judging quality of the container by the expansion dimension of saidcontainer outer walls.
 6. An inspection system of a container as setforth in claim 5 wherein said measuring means measures the expansiondimension of said container outer walls at a predetermined pressurereduction value of said pressure reduction process, and said processingmeans compares said measured value with a predetermined threshold value.7. An inspection system of a container as set forth in claim 5 whereinsaid air-tight container holds a plurality of inspected objects, andsaid measuring means and processing means function for each of theinspected objects.
 8. An inspection system of a container as set forthin claim 7 wherein a plurality of said air-tight containers are arrayedand alternately or successively connected to said conveying means, saidinspected objects are successively placed in said air-tight containers,and said inspected objects are discharged from inside said-air-tightcontainers to said conveying means.
 9. An inspection system of acontainer as set forth in claim 5 wherein said air-tight containerhouses a single inspected object.
 10. An inspection system of acontainer as set forth in claim 9 wherein a plurality of said air-tightcontainers are arrayed and successively connected to said conveyingmeans, said inspected objects are successively housed in said air-tightcontainers, and said inspected objects are discharged from inside saidair-tight containers to said conveying means.
 11. An inspection systemof a container as set forth in claim 5 which covers an inspected objectwith little air space or no air space in the container after thecontainer is filled with the liquid and an inspected object with nopositive pressure in the container.